1. Field of the Invention
This invention relates to the field of surgery, and more specifically to a device and method for guiding or applying force to a magnetic implant within the body of a patient.
2. Description of Related Art
It is known in the art to provide magnetic manipulation of diagnostic or therapeutic elements (which, for simplicity, we shall herein refer to collectively as "treatment implants") through body tissue or ducts (such as in vascular exploration or treatment). Systems providing for such manipulation are described in a number of previously published articles and patents, such as "Magnetically Guided Devices for Vascular Exploration and Treatment," Sadek K. Hilal et al., Radiology 113, 529-540 (1974); U.S. Pat. No. 3,358,676, entitled "Magnetic Propulsion of Diagnostic or Therapeutic Elements Through the Body Ducts of Animals or Human Patients," issued Dec. 19, 1967 to Ephraim H. Frei et al.; "Magnetic Manipulation Instrumentation for Medical Physics Research," George T. Gillies et al., Review of Scientific Instruments 65, 533-562 (1994); "Characteristics of an Improved Magnetic-Implant Guidance System," Robert G. McNeil et al., IEEE Trans. on Bio. Eng. 42(8) 802-808 (1995); "Functional Design Features and Initial Performance Characteristics of a Magnetic-Implant Guidance System for Stereotactic Neurosurgery," Robert G. McNeil et al., IEEE Trans. on Bio. Eng. 42(8) 793-801 (1995); and U.S. Pat. No. 5,654,864 to Ritter et al., entitled "Control Method for Magnetic Stereotaxis System," issued Aug. 5, 1997. All of these references are hereby incorporated in their entirety by reference. These systems all provide fixed or manually moved permanent magnets or electromagnets that are capable of applying fields and forces to treatment implants to move or guide the implant through a treatment region. However, because the magnets or electromagnets for these systems are large, it is difficult or impossible to provide complex imaging systems that can operate in conjunction with the magnetic guidance system. In addition, because of the limited ability to move the magnets or electromagnets, it is difficult to apply fields and forces accurately directed at accurately known locations.